This invention relates to a valve for valve-regulated electric storage batteries and a battery including a valve for regulating pressure within the battery. The invention has particular application in sealed batteries utilized in vehicles and as communication stand-by power systems. These types of batteries normally include some type of relief/check valve for venting hydrogen gas generated within the battery when the internal pressure of the gas within the battery exceeds a predetermined superatmospheric level. Ideally, such valves should vent gas frequently under very low pressure differential conditions, instead of infrequently venting large quantities of gas under high pressure differential conditions. The invention has application in batteries of the type having accessible access openings in the battery top as well as various types of batteries which are non-serviceable and which merely have a pressure regulating valve positioned into the battery top, but without removable battery caps or the like.
Such an ideal operation would require less robust battery cases, since pressure inside the case would be more constant and at a lower pressure. Therefore, the case could be made with less material, making it lighter and permitting correspondingly more lead to be added to the battery.
Such an ideal operation would also prevent ejection of water from the battery along with the vented hydrogen gas. This is a serious problem with long-life batteries, since a decrease in water in the battery reduces the power output and longevity of the battery.
Prior art battery valves include so-called "mushroom" or "burp" valves. These valves operate at relatively high pressure differentials. Another prior art valve type is the "cup" valve. This type of valve generally neither seals nor vents well, because tolerances between contacting parts must be very close.
Since venting in prior art valves takes place at relatively high pressure differentials, the gas is ejected from the battery with such force that it can carry droplets of water out of the battery through the vent along with the gas. In addition, the time taken for prior art valves to reseal is often excessive.
The valve according to this application achieves efficient gas venting under extremely low pressure differentials. The valve may be used in batteries where no pressure differential normally exists, or even where pressure inside the battery is lower than outside pressure.
To achieve this, the valve and the seal are in a single unit, as described and claimed below.